I have a 2003 f250 xlt with the 5.4l engine in it and lately my AC hasn't been standing up to the heat of the Midwest. When driving around town or on the highway my AC blows really cold but at idle you can tell a drop off in temp. Is this normal due to extreme heat or is there something I can do?

 

Try giving it a little recharge; might end up bring the simple solution. May just be a little low.

 

It could also be a failed fan clutch.

 

I'd take it to a qualified AC shop. They lose charge over time, that's completely normal. I wouldn't try to charge it yourself because the system is incredibly sensitive to weight of charge. It's not like topping off your oil when it's a quart low. The shop will completely evacuate the system and put in the correct amount.

 

Since you have a 2003 that uses r134a just go to an auto parts store and spend $30 on a recharge kit. You would spend more than that to get it in the door of an AC shop. Chances are you just need a little bit of a charge.


I did the same to my wife's VW a few years ago.

 

A little drop in efficiency is normal at a stop because there isn't as much air moving through the condenser as when you are moving...use the recirculation that should help.

if it is a drastic raise in Temps while at idle then take it in to have it looked at but just a little raise in temp while at idle, especially without the recirculation on, is perfectly normal.

 

This. The engine fan at idle doesn't move as much air as your truck cruising down the highway does. Also, when you're sitting still for any length of time, you start sweltering in your own heat, which reduces the efficiency of the condenser.

 

If the compressor isn't short cycling (indicating it could be low on freon) it's probably a combination of dirty condensor and lower airflow over it to cool. Try inspecting and washing of bugs and dirt first to see if you get an improvement. Also try running water over the condenser and see if idle temp improves.

 

Yes this is normal for two reasons. One, at idle the RMPs of the compressor is lower so it pumps less refrigerant. Two, at idle there is less air flowing through the condenser to take away the heat. Do not add any refrigerant just on a whim, because you could end up overcharging the system and creating another whole set of issues. Only add refrigerant if you've connected gauges and know for sure the low and high pressure readings are below spec.

 

Fot what it's worth, some refrigerant recharge cans come with the pressure dial.

 

You can usually rent AC manifold gauges for a refundable deposit at any auto parts store.

 

Yes but it only tells half the story. Not knowing what the high side is reading is still guesswork.

 

A good AC shop will hook up gauges and check pressure readings taking into account the air temp and humidity (which has been crazy high in the Midwest) and recommend a fix if needed. Check for a old time radiator repair shop. Good luck as they are getting far and fewer between.